The 33-year-old Strop posted a 2.26 ERA and 0.99 WHIP in 60 appearances in the 2018 season, arguably his best.
He also recorded 13 saves, including 11 after closer Brandon Morrow went down in mid-July.
Strop has posted a sub-3.00 ERA in each of his six seasons with the Cubs.
He is also a favorite in the clubhouse. In August, manager Joe Maddon had a special Strop-themed road trip, with players and the coaching staff dressing in his style — red on orange, green suits and lots of silver and gold chains.